Fuel system



E; O. WIRTH July 13, 1948."

FUEL SYSTEI Filed Oct; 19, 1944 Z'mi/ ATTDRNE Y engine operating variable.

Patented July 1:3, 1948 UNITED sr 'rss PATENT OFFICE FUEL SYSTEM Bend, Ind., assignor to Emil 0. Wirth, South Bendix Aviation Corpora tion, South Bend, 11111.,

a corporation of Delaware Application October 19, 1944, Serial No. 559,434 4 Claims. (Cl. 261-37) This invention relates to fuel systems for internal combustion engines and the like and more particularly to pressure fuel systems wherein the fuel is delivered to the carburetor or engine under superatmospheric pressure and contains subject matter in common with the following applications: Leibing and Fageol, Serial No. 533,848, flied May 3, 1944, in which is disclosed a fuel supply system having a movable flow responsive member provide a fuel system of this character of simple construction and having improved performance and economy.

A further object of the invention is to provide a device of this character adapted to control the fuel pressure in accordance with at least one A still further object is to provide means for modifying said pressure in accordance with barometric pressure.

The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawing which represents a preferred embodiment thereof. After considering the example, skilled persons will understand that many variations may be made without departing from the principles disclosed, and I contemplate the employment of any structures, arrangements, or modes of operation that are properly within the scope of the appended claims.

The accompanying drawing is a diagrammatical view showing a fuel system as a whole wherein the present invention is embodied.

While the present invention is shown and described in connection with a downdraft carbure-.

tor having a movable flow responsive member in the induction passage for controlling the inflow of fuel to said passage. it is to be understood that the present invention may be used in other types of fuel systems, such as those employing other flow responsive means, which means may includethe like for controlling the meterdiaphragms or .The invention may also be used ing of the fuel.

teaches a pressure in connection with carburetors of the updraft or horizontal delivery type.

Thefuel system, as shown, comprises the usual fueltank l0 connected by a conduit II to afuel pump ll of known construction. The pump may be of the diaphragm type commonly used on present day installations, but for simplicity is as a gear pump having a by-pass l6 controlled by a pressure responsive valve 18 set for a predetermined pressure. Whatever the type of pump, it should supply fuel to the carburetor at a substantially constant pressure and should preferably prevent flow through the line when the engine is not operating. An outlet line 20 leads from the pump to a pressure regulator indicated generally at 22, and thence is conveyed by a conduit 24 to a separating chamber, not

' shown herein but preferably of the character of that shown and described in the above Leibing and Fageol application, there being a return'line 26 which conveys excess fuel, together with any vapor which may be present in the line, back to the tank Ill. The return line 26 is preferably provided, at its point of connection with the chamber, with a restriction (shown in said Leibing andrFageol application) of such size as to permit pressure to be built up in the chamber.

From the separating chamber fuel is conveyed to a nozzle 28 of the carburetor, indicated generally at 30, and the discharge of fuel into the induction passage is controlled by a fuel valve 32 controlled through a lever 34 in accordance with certain engine operating conditions, which as shown herein and described hereinafter, comprises means responsive to fluid flow through the induction passage of the carburetor. This fluid flow responsive means is adapted to so control the flow of fuel into the induction passage as to proportion said fuel in accordance with the mass air flow through said induction passage.

The carburetor generally spring, notshown, yieldingly urges the vane in shown 3 the closing direction. The mixture outlet 33 is ing direction by said lever and is urged in the' closing direction by a spring 00, it being noted that the pressure of fuel on the valve has little or no, effect on the action of said valve, that is the valve is operable substantially independent of fuel pressure thereon.

The carburetor may also include such other elements, not shown herein but fully disclosed in the above Leibing and Fageol application. as are compatible with the present arrangement, said means being adapted to variably control the characteristics of the fuel mixture under various predetermined operating conditions.

Fuel regulator Suitable means for regulating or controlling the pressure of the fuel delivered to the carburetor induction passage is provided and is interposed in the fuel line between the pump I4 and the carburetor. The regulator comprises a body having a central casing member 64 which includes an inlet 65 connected with the conduit 20 from the fuel pump and an outlet 66 connected with the conduit 24 to the carburetor. A hollow end member 61 is secured to one side of the central member 64 by any suitable means such as screws 68, and a second hollow member I secured to the opposite side of the central member 64 by screws 12. A flexible diaphragm I4 is secured between the casing members I0 and 64 thereby separating the interior of the regulator into two chambers, I6 and 18. The former chamber is a fuel chamber and the latter is connected with a venturi 80 in the induction passage by a conduit 82, which may, if desired, be provided with a calibrated restriction 84. I6 is a valve, indicated generally at 35, which is connected to the inlet 65 by conduit 88. The valve includes a seat 90 adapted to be engaged by a movable valve member 92 connected to the diaphragm I4 by a valve stem 94. A spring I00 is disposed in the chamber I8 and is adapted to react between the diaphragm I4 and a spring retainer I02. The spring retainer has a central recess in which is received the tapered end I04, a screw I08 screwed into the adjacent end wall I08 of the member I0. By turning the screw inwardly or outwardly the tension of the spring is manually varied and a lock nut H0 is provided for locking the screw I08 in adjusted positions.

Fuel under substantially constant pump pressure, entering the regulator by way of the inlet 65. passes through valve 86 and into the chamber 16 and urges the diaphragm downwardly in opposition to the upwardly exerted force of spring I00, so that the valve 80 is controlled primarily by the pressures on opposite sides of the diaphragm, and the effective force urging the valve 86 closed determines the fuel pressure posterior to the regulator. Further, with the above arrangement the pressure of fuel to the carburetor may be varied by varying one of the above pressures on the diaphragm I4.

Barometric control means sponsive device indicated generally at I20. This device comprises a casing I22 within which an expansible bellows I24 is disposed. The bellows is attached at one end to a reservoir I28 screwed into the upper endof the casing I 22. The bellows is adapted to be filled with a liquid and the reservoir is partly filled with such liquid, the upper portion of the reservoir being filled with a gas and communication is provided between the reservoir and the bellows by a calibrated passage I23 which is adapted to so restrict the flow of liquid between the reservoir and the bellows as to damp fluctuations thereof. A conduit I30 leads from the air entrance 36 of the carburetor to the interior of the casing I22 and a passage I34 leads from the interior of the casing I32 to a passage I 36 controlled by a valve I23 secured to the free end of the bellows, the valve member I38 having a tapered point I40 adapted to cooperate with a valve seat I42 of said passage I38. A conduit I44 connects the passage I 36 and the con uit 82. With this arrangement air may be bled from the air inlet 38 v to the conduit 32 for varying the suction trans- Within the chamber vantages, the form hereinbefore mitted from the venturi to the chamber "I3 of the regulator unit, the quantity of air thus bled being controlled by atmospheric pressure or pressure at the air inlet which is transmitted to the interior I32 of the casing I22.

Should the present device be installed on an aircraft the fuel mixture will be maintained at the proper ratio as the aircraft changes altitude due to the barometric control. As the aircraft rises, for example, the pressure in the inlet 35 will decrease and result in a decrease of pressure in the chamber I32 of the barometric control unit I20 whereupon the bellows will expand and reducethe amount of air bled to the conduit 32 so that an increase in suction will be transmitted from the venturi to the chamber I8 and result in increasing the closing force on the valve member 92 which in turn will result in a decrease in the pressure of fuel posterior to the regulator to compensate for the reduction in the density of the air being taken into the induction passage of the carburetor. When the aircraft descends into denser atmosphere the operation of the device will be the reverse of that above described and an increase in the supply of. fuel will be effected. I

It is thought that the invention and many of its attendant, advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material addescribed being merely a preferred embodiment thereof.

I claim:

1. In a fuel system for an internal combustion engine: an induction passage having an air inlet and a mixture outlet controlled by a throttle valve; a movable member anterior to the throttle and adapted to 'be actuated by air flow in the induction passage; a fuel nozzle; a substantially constant delivery fuel pump; means connecting said pump and said nozzle; valve means controlled by the movable member for controlling the delivery of fuel to the induction passage, said valve being substantially unresponsive to fuel pressure; regulating means for varying the .ratlo of fuel to air uniformly to the engine by modifying the pressure of fuel anterior to the fuel valve; a venturi in the induction passage anterior to the throttle; a connection between theventuri and the regulator means whereby the latter is controlled in accordance with Venturi suction;

means for bleeding air from the air inlet of the induction passage to said connection for modifying the Venturi suction; and means responsive to barometric pressure for controlling the bleed means.

2. In a fuel system for an internal combustion engine: an induction passage having an air inlet and a mixture outlet controlled by a throttle valve; a movable member anterior to the throttle adapted to be actuated by air flow in the induction passage; a fuel nozzle; a source of fuel at a substantially constant pressure; a conduit connecting said source and said nozzle, including a metering orifice therein; a valve means controlled by a movable member for controlling the effective area of the metering orifice; regulating means for varying the ratio of fuel to air for the engine by modifying the pressure of the fuel anterior to the fuel valve; a venturi in the induction passage anterior to the throttle; a connection between the venturi and the regulator means whereby the latter is controlled in accordance with Venturi suction; and means for bleeding air into said connection for modifying the Venturi suction.

3. In a fuel system for an internal combustion engine having an induction passage with a venturi and a throttle valve therein; a vane anterior to the throttle adapted to be actuated by air stream from said member; an air chamber; a

movable wall separating said chambers; a passage connecting said air chamber with the venturi,

said movable wall being connected to said valve member and adapted to actuate said member in accordance with the differential in pressure between said chambers; and a yieldable means urging said movable wall in the direction to open said valve member.

4. In a fuel system for an internal combustion engine having an induction passage with a venturi and a throttle valve therein; a vane anterior to the throttle adapted to be actuated by air flow in the induction passage; a fuel nozzle; a source of fuel at a substantially constant pressure; a conduit connecting said source with said nozzle, including a metering orifice therein; a

valve controlled by the vane for controlling the 10 effective area of the metering orifice; a regulating means for varying the ratio of fuel to air by modifying the pressure of the fuel anterior to the fuel valve, said regulating means comprising a valve member; 'a chamber for fuel downstream from said member; an air chamber; a movable wall separating said chambers; a passage connecting said air chamber with the venturi in the induction passage, said movable wall being connected to said valve member and adapted to actuate said member in accordance with the difierential in pressure between said chambers; a yieldable means urging said movable wall in the direction to open said valve member; an air bleed for modifying the Venturi pressure in said air chamber; and a means responsive to barometric prcssure for controlling said air bleed.

151M111 O. WTRTH. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name I Date 1,855,383 Capell Apr. 26, 1932 2,223,381 Mock Dec. 3, 1940 2,234,001 Gistucci Mar. 4, 1941 2,318,216 Garretson May 4, 1943 40 2,330,650 Weiche Sept. 28, 1943 2,348,008 ,Hunt May 2, 1944 2,348,113 'Davis May 2, 1944 2,372,356 Chandler Mar. 27, 1945 n FOREIGN PATENTS Number Country Date 542,761 Great Britain Jan. 27, 1942 OTHER REFERENCES Ser; No. 394,322, Gosslau et al. (A. P. C.) pub.

May 25, 1943. 

